Techniques have previously been proposed for providing the feet of a legged mobile robot with bendable toes. Examples of this type of legged mobile robot include, for example, the technology set out in Patent Reference 1. In the technology according to Patent Reference 1, a configuration is adopted which provides a vertically rotatable toe formed at the fore end of the foot and a lock mechanism for locking rotation of the toe at the position where the bending angle of the toe is zero degree (substantially horizontal) and ensures the required contact area at floor contact by locking the rotation of the toe before the leg touches down and the toe is retractively rotated (bent) during toe-off by releasing the lock before the leg lifts off.
Patent Reference 1: Japanese Laid-open Patent Application No. 2003-236777 (particularly paragraphs 0011, 0012, FIG. 2 and FIG. 10)